title: Prenatal mercury exposure and infant birth weight in the Norwegian Mother and Child Cohort Study.
abstract: OBJECTIVE
  To examine the association between calculated maternal dietary exposure to Hg in pregnancy and infant birth weight in the Norwegian Mother and Child Cohort Study (MoBa).
  
  
  METHODS
  Exposure was calculated with use of a constructed database of Hg in food items and reported dietary intake during pregnancy. Multivariable regression models were used to explore the association between maternal Hg exposure and infant birth weight, and to model associations with small-for-gestational-age offspring.
  
  
  METHODS
  The study is based on data from MoBa.
  
  
  METHODS
  The study sample consisted of 62 941 women who answered a validated FFQ which covered the habitual diet during the first five months of pregnancy.
  
  
  RESULTS
  Median exposure to Hg was 0·15 μg/kg body weight per week and the contribution from seafood intake was 88 % of total Hg exposure. Women in the highest quintile compared with the lowest quintile of Hg exposure delivered offspring with 34 g lower birth weight (95 % CI -46 g, -22 g) and had an increased risk of giving birth to small-for-gestational-age offspring, adjusted OR = 1·19 (95 % CI 1·08, 1·30). Although seafood intake was positively associated with increased birth weight, stratified analyses showed negative associations between Hg exposure and birth weight within strata of seafood intake.
  
  
  CONCLUSIONS
  Although seafood intake in pregnancy is positively associated with birth weight, Hg exposure is negatively associated with birth weight. Seafood consumption during pregnancy should not be avoided, but clarification is needed to identify at what level of Hg exposure this risk might exceed the benefits of seafood.
authors.affiliation: 1Division of Epidemiology,Norwegian Institute of Public Health,Post Box 4404 Nydalen,NO-0403 Oslo,Norway.
authors.forename: Kristine
authors.initials: K
authors.lastname: Vejrup
authors.affiliation: 2Division of Environmental Medicine,Norwegian Institute of Public Health,Oslo,Norway.
authors.forename: Anne Lise
authors.initials: AL
authors.lastname: Brantsæter
authors.affiliation: 2Division of Environmental Medicine,Norwegian Institute of Public Health,Oslo,Norway.
authors.forename: Helle K
authors.initials: HK
authors.lastname: Knutsen
authors.affiliation: 1Division of Epidemiology,Norwegian Institute of Public Health,Post Box 4404 Nydalen,NO-0403 Oslo,Norway.
authors.forename: Per
authors.initials: P
authors.lastname: Magnus
authors.affiliation: 3Office of Director-General,Norwegian Institute of Public Health,Oslo,Norway.
authors.forename: Jan
authors.initials: J
authors.lastname: Alexander
authors.affiliation: 2Division of Environmental Medicine,Norwegian Institute of Public Health,Oslo,Norway.
authors.forename: Helen E
authors.initials: HE
authors.lastname: Kvalem
authors.affiliation: 2Division of Environmental Medicine,Norwegian Institute of Public Health,Oslo,Norway.
authors.forename: Helle M
authors.initials: HM
authors.lastname: Meltzer
authors.affiliation: 2Division of Environmental Medicine,Norwegian Institute of Public Health,Oslo,Norway.
authors.forename: Margaretha
authors.initials: M
authors.lastname: Haugen
mesh_terms: D001724:Birth Weight / Q000187:drug effects; D015331:Cohort Studies; D016208:Databases, Factual; D005247:Feeding Behavior / Q000208:ethnology; D005260:Female; D005317:Fetal Growth Retardation / Q000139:chemically induced* / Q000453:epidemiology / Q000208:ethnology; D005506:Food Contamination; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008297:Male; D039382:Maternal Nutritional Physiological Phenomena / Q000208:ethnology; D008628:Mercury / Q000032:analysis / Q000633:toxicity*; D009664:Norway / Q000453:epidemiology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000208:ethnology; D011446:Prospective Studies; D012306:Risk; D017747:Seafood / Q000009:adverse effects* / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D008628:Mercury